我有个问题：

select 

a.item_page_productid,
b.category_id,
a.viewcount

from 

(select 
item_page_productid,
count(*) as viewcount
from views 
where  eventdate > to_date(days_sub(now(), 60))
group by item_page_productid
) a

join

(select
 product_id,
 category_id
 from catalog_products_in_categories
 where active = 't') b

 on a.item_page_productid=b.category_id

我要做的是将单个item\u page\u productid与单个category\u id配对，并将item\u page\u productid配对为具有最高viewcount的项。
有什么想法吗？